Re: Is there ways to make a atk factory only used for some instances

[Bolian Yin <bolian yin sun com>]

HI Bill and Padraig,

Thanks a lot.  I understand your explanation. The problem is that the 
code has been there for some time, I need to show the people in ximian 
that it is necessary to add a new subtype to replace the current 
implementation. I will try that anyway.

> How do you distinguish betwenen a jump button and other types of 
> GnomeCanvasPixbuf. 

I cannot, that is why I ask this question. If there is a new subtype of 
GnomeCanvasPixbuf, I can.

> I have had a look at the code in gail and there is no specific support 
> for GnomeCanvasPixbuf. Do you need additions to gail?
I don't need the additions to gail for this case. I think deriving from 
GailCanvasItem will be enough for the jump button.

-Bolian

> Padraig
>
>
> Bolian Yin wrote:
>
> > Hi Bill and Padraig,
> >
> > Please see the attached picture. The "jump button" (the little yellow 
> > rectangle) is the gnome-canvas-item in question, more accurately, it 
> > is a gnome-canvas-item-pixbuf.  The "jump button" is used to indicate 
> > that there are more events that are not displayed in the day.  Now I 
> > have make it focusable, can jump to the day on receving a Enter Key, 
> > then all the events of the day can be displayed.  This is the action 
> > that I want to export through the atk action interface.
> >
> > In the current implementation of the jump button in evolution, there 
> > are no new subclass to GnomeCanvasPixbuf, see the code below:
> >
> > -- code snip begins 
> > ----------------------------------------------------------------------------------- 
> >
> >
> >     /* Create the buttons to jump to each days. */
> >     pixbuf = gdk_pixbuf_new_from_xpm_data ((const char**) jump_xpm);
> >
> >     for (i = 0; i < E_WEEK_VIEW_MAX_WEEKS * 7; i++) {
> >         week_view->jump_buttons[i] = gnome_canvas_item_new
> >             (canvas_group,
> >              gnome_canvas_pixbuf_get_type (),
> >              "GnomeCanvasPixbuf::pixbuf", pixbuf,
> >              NULL);
> >
> >         g_signal_connect (week_view->jump_buttons[i], "event",
> >                   G_CALLBACK (e_week_view_on_jump_button_event), 
> > week_view);
> >     }
> >
> > /* ... omitted */
> >
> > e_week_view_on_jump_button_event (GnomeCanvasItem *item,
> >                   GdkEvent *event,
> >                   EWeekView *week_view)
> > {
> >
> >     /* ... omitted */
> >
> >     else if (event->type == GDK_KEY_PRESS) {
> >         /* return, if Tab, Control or Alt is pressed */
> >         if ((event->key.keyval == GDK_Tab) ||
> >             (event->key.state & (GDK_CONTROL_MASK | GDK_MOD1_MASK)))
> >             return FALSE;
> >         /* with a return key or a simple character, jump to the day */
> >         if ((event->key.keyval == GDK_Return) ||
> >             ((event->key.keyval >= 0x20) &&
> >              (event->key.keyval <= 0xFF))) {
> >             e_week_view_jump_to_button_item (week_view, item);
> >             return TRUE;
> >         }
> >     }
> >
> >     /* ... omitted */
> > }
> > -- code snip end 
> > ----------------------------------------------------------------------------------- 
> >
> >
> >
> > So, the "action" is only supported through the signal handler to 
> > GnomeCanvasPixbuf "event" signal, not in a new subclass. My aim is to 
> > support this action only in the jumpbutton instances, not in any 
> > other instances of GnomeCanvasPixbuf.
> >
> > Thanks,
> > -Bolian
> >
> >
> > Bill Haneman wrote:
> >
> > > Bolian:
> > >
> > > The best way to ensure that an AtkFactory is used only with certain
> > > instances of a GObject type is to create a new subtype.  In your case,
> > > this means that GnomeCanvasItem should be subclassed, and an 
> > > appropriate
> > > AtkFactory registered for the new type or types. 
> > > GnomeCanvasItem is already an abstract class, so you must already be
> > > using subclasses.  If your GnomeCanvasItems are instances of existing
> > > GnomeCanvas subtypes, for instance GnomeCanvasWidget instances, you may
> > > need to create something like a GnomeCanvasActiveWidget type which is
> > > used for your 'actionable' canvas items.
> > >
> > > regards
> > >
> > > Bill
> > >
> > > On Thu, 2003-09-04 at 08:06, Bolian Yin wrote:
> > >  
> > >
> > > > Hi Padraig,
> > > >
> > > > I met the problem in gnome-canvas-item. Gail has impl for 
> > > > gnome-canvas-item, but programmers can add many functions to a 
> > > > gnome-canvas-item.
> > > >
> > > > For example, a gnome-canvas-item support an action in some context, 
> > > > and want to add a action interface to the atkobject creates for it. 
> > > > In this case, I cannot register a new factory to create the atk 
> > > > object, or all the gnome-canvas-items will create their atk objects 
> > > > using the new factory.
> > > > Is there ways to make a atk factory only used for some instances of 
> > > > gnome-canvas-item, and in other case the default (gail) factory 
> > > > will be used?
> > > >
> > > > Thanks,
> > > > Bolian
> > > >
> > > >
> > > >   
> > >
> > >
> > >
> > >  
> >
> >
> > ------------------------------------------------------------------------